Electrolyzed Oxidizing (EO) water and other electrochemically activated liquids are produced by a somewhat simple process of electrolysis. Michael Faraday discovered electrolysis in 1859. Common electrolysis applications include electroplating metals onto other surfaces and the manufacture of household bleach. Today, electrolysis is at the forefront of our energy program. Electrolysis is used to split water molecules to produce hydrogen fuel for fuel cells. EO water generators using the same principals split common salt (sodium chloride as an example) into two special solutions, acidic and alkaline.
A typical electrolysis cell has at least one positive electrode (anode) and at least one negative electrode (cathode), which are separated by an ion-selective membrane to create an anode chamber and a cathode chamber. As the liquid is passed through the chambers, an electric field applied across the electrodes electrochemically activates the liquid by collecting positive ions (e.g., cations, H+) on one side of the membrane and collecting negative ions (e.g., anions, OH−) on the opposing side. The liquid in the chamber having the cations is thereby rendered acidic (i.e., a catholyte EA liquid) and the liquid in the chamber having the anions is correspondingly rendered alkaline (i.e., an anolyte EA liquid).
Electrolysis of water typically requires no chemicals, with essentially nothing added to the water. Electrolyzed alkaline and acidic waters are non-toxic cleaning and sanitizing solutions that can replace chemical detergents and biocides. The advantages of these solutions are lower costs than chemical products, non-toxic to humans, non-drying to skin when used for disinfections, leaves no residues, and microorganisms cannot develop an immunity to the electrical characteristics of the water.
Specific properties of acidic EA water include an extremely high ORP (oxidation-reduction potential), with a small concentration of hypochlorous acid and a low pH. The high ORP value can be above +1200 millivolts, but more typically around +800 millivolts. A millivolt is commonly defined as a measure of the potential energy of a unit charge at a given point in a circuit relative to a reference point (ground). The high ORP value means the solution will take electrons from other molecules, thereby providing improved sanitizing properties. Acidic EA water has a pH value of less than 7.0. The lower pH on the acid side means the higher concentration of hydrogen ions.
Alkaline EA water can replace general purpose cleaners and detergents. One of the specific properties of alkaline EA water is an extremely low ORP. Alkaline EA water has a negative ORP (oxidation reduction potential) in the range of −400 millivolts to −1000 millivolts, for example. The negative ORP means an absence of oxygen. This water is also called “reduced water”. Another property of alkaline EA water is a high pH value. Solutions with pH values greater than 7.0 are alkaline.
Commonly, when alkaline water is used for cleaning the acid water with the low pH and high OPR is disposed of into the sewer system of the building. When acidic water is used for sanitizing purposes, the alkaline water with high pH and low ORP is disposed of into the sewer system.
With that said, rules for sewer disposal restrictions and standards vary from city to city, state to state and country to country. The present disclosure pertains to methods and apparatus for neutralizing the alkaline or acidic waste stream before entering the city sewer system, for example. It also pertains to waste water when used in a cleaning situation such as that of a mop and bucket, an automated scrubber/dryer or soft floor maintenance/cleaning.
Various methods of neutralizing alkaline and acidic streams have primarily involved recombining the unused waste stream with the used stream in some fashion. A practical example would be using the alkaline EA water as the primary solution for a purpose such as hard or soft floor surface cleaning. After use, the used alkaline stream in combination with waste products could be blended with the unused acid stream for recombination before disposal. The recombination results in a near instant neutralization of both the alkaline and acidic solutions.
Tennant Company has created a device and process that recombines acidic and alkaline solutions prior to applying the working water to a surface to be cleaned and/or sanitized. For example, modified pH 3 acidic water and pH 11 alkaline water are recombined into a single output stream. The recombined waters are held separated by nanobubbles to obtain a cleaning solution working life of up to 45 seconds, for example. The newly created solution briefly retains the known benefits of acidic and alkaline solutions for the working life and then self-neutralizes.
Another common method of neutralizing electrolyzed wastewater is to let the alkaline and/or acid solutions to sit in open containers to neutralize over time. This method typically requires 24 hours before the liquids reach a safe neutral pH before disposal into sewer system. This method can be inconvenient.
Yet another method of neutralizing electrolyzed wastewater involves organic loading of the alkaline or acid solution. Typically, the alkaline or acid solution will tolerate a 5% organic load before reaching a neutral state over time.
Yet another method includes chemical inducement to neutralizing the streams. However, the added chemicals can increase the cost of the neutralization process.